This is an unofficial app that helps you activate Android night mode theme on devices that do not provide this option in the system settings.
This setting only works on apps that support night mode theme such as Instagram google play store and etc.

This app will not work on all devices since some smartphone manufacturers have disabled or blocked this option for their devices!
For using night mode on android below 5 there is an option called Driving Mode which should be enabled and the app will automatically do it for you.
When Driving Mode is active:
• Incoming message notifications are muted.